JP5161743B2 - Inspection device and inspection method for glass sealing part - Google Patents

Description

  The present invention relates to a glass sealing portion inspection apparatus and a glass sealing portion inspection method provided in a glass terminal or the like.

  2. Description of the Related Art An optical semiconductor device in which an optical element is mounted includes a product that is formed by glass-sealing a lead that becomes a signal line or the like on an eyelet that mounts an optical element. FIG. 11A shows a cross-sectional view of a portion where the lead 10 of the optical semiconductor device is glass-sealed. The lead 10 is inserted into an insertion hole 12 a provided through the eyelet 12 in the thickness direction, and the insertion hole 12 a is filled with glass 14 and hermetically sealed to the eyelet 12.

Such a glass sealing portion is required to be filled and sealed with a sufficient amount of glass 14 in the insertion hole 12a. This is to ensure airtightness in the glass sealing portion and to ensure wire bonding to the lead 10. This is because if the amount of the glass 14 supplied to the insertion hole 12a is small, the support of the lead 10 is lowered, and sufficient bonding strength may not be obtained when wire bonding to the lead 10 is performed.
For this reason, in the inspection process, it is inspected whether or not a required amount of glass 14 is filled in the glass sealing portion. The criterion for determining whether or not the glass sealing portion is filled with the required amount of glass 14 is that the dent D (FIG. 11B) of the glass 14 in the insertion hole 12a is not more than a certain value (for example, 0.5 mm or less). ) Is a good idea.
JP-A-10-10053 JP-A-7-58500

The inspection about the glass sealing part of the eyelet 12 is conventionally performed by visual observation. Therefore, there is a problem that the inspection of the glass sealing portion is inefficient and the inspection results vary.
As a method for inspecting the glass filling state of the glass sealing portion without visual observation, for example, there is a method using an apparatus for measuring a displacement in the height direction from a reference position, such as a laser focus type displacement sensor. However, in the case of a method for detecting the height at a specific point, such as a laser focus type displacement sensor, it is necessary to measure a plurality of points in the glass sealing portion, and the height can be measured accurately. There is a problem that the measurement becomes complicated. Although it is possible to perform measurement using a microlens, there is a problem that the apparatus is expensive.

  When inspecting the surface state of glass such as the glass sealing part of the glass terminal, the present invention can inspect the surface state of the glass efficiently and reliably without using an expensive inspection device. It aims at providing the inspection apparatus and inspection method of a sealing part.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, in the inspection apparatus for the glass sealing portion, a support portion that supports the inspection object including the glass sealing portion at the inspection position, and a ring shape that is disposed above the inspection object and illuminates the inspection object A ring illumination unit in which a light source is disposed, and an imaging optical system for photographing the glass sealing unit together with an image of the light source of the ring illumination unit reflected in the glass sealing unit through an opening of the ring illumination unit, An image analysis unit that analyzes image data captured by an imaging optical system and analyzes a surface state of glass in the glass sealing unit is provided. Note that the ring illumination unit in which the light sources are arranged in a ring shape includes both cases where the light sources are continuously arranged in the circumferential direction and cases where the light sources are arranged at predetermined intervals in the circumferential direction. It is. Moreover, the surface state of glass means the height position of the glass surface with respect to the reference height position, the unevenness of the glass surface, the inclined state, and the like.

The imaging optical system has a depth of field so that the displacement of the surface position of the glass in the glass sealing part is captured as a change in the focus state of the light source image of the ring illumination part reflected in the glass sealing part. Is set, the brightness of the image data can be analyzed by the image analysis unit to analyze the glass surface state of the glass sealing unit.
In addition, the image analysis unit includes means for measuring the frequency distribution of the brightness of the image data, so that the surface state of the glass can be accurately grasped.
In addition, the image analysis unit includes means for differentiating the image data and converting the image data into brightness of the image data, so that the surface state of the glass can be grasped more accurately.

  Moreover, it is an inspection method for inspecting the surface state of the glass provided in the glass sealing part of the test object including the glass sealing part, and the test object including the glass sealing part is illuminated by the ring illumination part. A step of photographing the glass sealing part together with an image of the light source of the ring illumination part reflected in the glass sealing part using an imaging optical system; and an image photographed by the imaging optical system by an image analysis part. Analyzing the data and analyzing the surface state of the glass in the glass sealing portion, and the imaging optical system includes a displacement of the surface position of the glass in the glass sealing portion reflected in the glass sealing portion. In the step of analyzing the surface state of the glass, the brightness distribution of the image data is set to be captured as a change in the focus state of the image of the light source of the ring illumination unit. Comprising the step of measuring, and detecting the state of the surface of the glass based on the brightness histogram of the image data.

Further, in the step of illuminating the object to be inspected by the ring illumination unit, it is possible to inspect the substantially entire surface of the glass surface of the glass sealing unit by using a ring illumination unit in which a light source is arranged in an annular shape. .
Further, the step of analyzing the surface state of the glass by the image analysis unit includes a step of differentiating image data, and the step of measuring the frequency distribution of the brightness of the image data is performed with the differentiation process. By measuring the frequency distribution of the image data, the surface state of the glass in the glass sealing portion can be inspected with high accuracy.
Further, in the step of analyzing the surface state of the glass by the image analysis unit, the surface state of the glass can be detected with higher accuracy by providing a step of removing unnecessary portions of the image data.

  Further, in the case where a glass terminal including a glass sealing portion in which a lead is glass-sealed in an eyelet is used as an inspection object, a light source is arranged in an annular shape in the step of illuminating the inspection object by the ring illumination section. In the step of analyzing the surface state of the glass by the image analysis unit, using the ring illumination unit, a step of differentiating the image data, and a step of removing unnecessary portions of the lead and the eyelet from the image data And a step of measuring a frequency distribution for the image data subjected to the differentiation process.

  According to the inspection apparatus and the inspection method for the glass sealing portion according to the present invention, the glass sealing portion is illuminated by the ring illumination portion, and the image of the light source reflected in the ring illumination portion is taken by the imaging optical system. The surface state of the glass in the glass sealing part can be easily inspected.

Hereinafter, as an application example of the inspection apparatus and inspection method for a glass sealing portion according to the present invention, an example of inspecting a glass sealing portion in which a glass terminal lead is glass-sealed will be described.
(Configuration of inspection equipment)
In FIG. 1, schematic structure of the test | inspection apparatus used for the test | inspection of the glass sealing part of a glass terminal is shown. An inspection unit for inspecting the glass terminal 20 that is an object to be inspected is a set base 22 for positioning and setting the glass terminal 20, a ring illumination unit 24 disposed above the set base 22, and an upper part of the ring illumination unit 24. And an imaging optical system 30 disposed coaxially with the ring illumination unit 24.

The glass terminal 20 is obtained by glass-sealing two leads 21 on an eyelet. The set base 22 is provided with an insertion hole into which the lead 21 extending downward from the eyelet is inserted. The peripheral edge of the eyelet is locked to the edge of the insertion hole, and the glass terminal 20 is supported by the set base 22. The
The ring illumination unit 24 is attached to a lower surface of a support body having a ring shape in a planar shape so that a large number of LEDs 24a are adjacent to each other in a circumferential arrangement. In the embodiment, a red LED is used as a light source for illumination. The light source color of the light source is not particularly limited. The outer peripheral diameter of the support of the ring illumination unit 24 is 50 mm, and the inner peripheral diameter of the support is 28 mm. The ring illumination unit 24 is connected to an illumination power source 25, and lighting is controlled by the illumination power source 25.

  The imaging optical system 30 includes an optical lens 26 and a CCD camera 28. The CCD camera 28 has a field of view of 2.1 mm × 1.6 mm, a resolution of 640 pix × 480 pix, and a resolution of 3.3 μm / pix. The diameter of the glass sealing part provided in the glass terminal 20 of the object to be inspected is 1.1 mm. The CCD camera 28 is set so that the entire glass sealing portion can be captured as an image within the field of view.

  As an analysis unit for an image captured by the CCD camera 28, an image analysis unit 32, an input unit 34, and a monitor 36 are provided. The image analysis unit 32 is connected to the CCD camera 28, and the input unit 34 and the monitor 36 are connected to the image analysis unit 32.

(Imaging optical system settings)
The ring illumination unit 24 is arranged above the glass terminal 20 that is the object to be inspected, and the imaging optical system 30 is arranged concentrically with the center line position of the ring illumination unit 24. This is because the glass sealing portion of the glass terminal 20 can be visually recognized by the CCD camera 28 through the opening 24b.
In this embodiment, an image of the light source to the glass sealing portion is arranged in a ring in the ring illumination unit 24 copies of the glass terminal 20 interrupt useless image of the light source reflected by the glass sealing portion in other words the CCD The imaging optical system 30 is arranged in an arrangement visually recognized by the camera 28.

FIG. 2 shows a state of an image of the glass sealing portion visually recognized by the CCD camera 28.
FIG. 2A shows a case where the surface of the glass 14 filled in the glass sealing portion is concave (convex downward in the figure). In this case, as shown in the photograph, the image of the light source reflected on the glass of the glass sealing portion is a double ring. The reason why the image is seen in a ring shape is that the light sources are arranged in a ring shape. In the image, a lead (white portion at the center) inserted in the center of the insertion hole, the surrounding glass (black portion), and the circular edge of the insertion hole are shown.

FIG. 2B shows a state where the surface of the glass 14 filled in the glass sealing portion is convex. In this case, an image of the light source appears in a single ring shape as shown in the photograph.
FIG. 3 shows the principle that the image of the light source is single and double when the surface of the glass 14 filled in the glass sealing portion is convex or concave.
FIG. 3A shows a case where the surface of the glass 14 has a convex shape. In this case, the reflected light at the position of point A, which is the curved surface of the glass 14 (or the boundary portion between the curved surface and the flat surface). A single ring-shaped image is visually recognized. On the other hand, when the surface of the glass 14 is concave, as shown in FIG. 3B, the curved surface (boundary portion between the curved surface and the plane) has two points, point B and point C. As a result, a double ring-shaped image is obtained.

  FIG.2 (c) is a state where the filling amount of the glass 14 in a glass sealing part is small, and the surface position of the glass 14 is in a very low position seeing from the surface of an eyelet. In this case, the image of the light source visually recognized by the CCD camera 28 is a blurred image.

  In the setting of the imaging optical system in the present embodiment, in addition to setting so that the image of the light source of the ring illumination unit 24 is reflected in the glass sealing part, the filling state of the glass 14 in the glass sealing part is glass sealed. The optical system is set so as to be captured as a change in the focus state of the image of the light source reflected on the stop, in other words, a change in the brightness of the image of the light source. When the position of the surface of the glass 14 is displaced with respect to the surface of the eyelet with respect to the surface of the eyelet, the image of the light source visually recognized by the CCD camera 28 is blurred because of such setting.

  The quality determination of the filling state of the glass 14 in the glass sealing portion is determined by how much the surface of the glass 14 of the glass sealing portion is below (low) with respect to the surface of the eyelet. In the present embodiment, it is determined as defective when the surface of the glass 14 is displaced more than 0.5 mm below the surface of the eyelet. Therefore, the optical system for visually recognizing the glass sealing portion is a light source that is reflected in the glass sealing portion when the height position of the surface of the glass 14 in the glass sealing portion is displaced by about 0.5 mm with respect to the surface of the eyelet. It is set so that it can be accurately captured as a change in luminance of the image.

  Considering the manufacturing process of the glass terminal, it is sufficiently conceivable that the glass portion of the glass sealing portion varies and the height position of the glass surface varies by about ± 0.1 mm. Therefore, a variation of about ± 0.1 mm is allowed as a measurement error in determining the quality of the glass sealing portion. For this reason, in this embodiment, measurement was performed with the depth of field of the optical system set to ± 0.05 mm.

(Inspection method of glass sealing part)
A method for inspecting the glass filling state in the glass sealing portion using the inspection apparatus shown in FIG. 1 is shown in FIG. 4 as a flowchart.
First, the glass terminal 20 that is the object to be inspected is set on a set base 22 as a support part of the object to be inspected, and the glass sealing portion of the glass terminal 20 is aligned within the field of view of the CCD camera 28. A glass sealing part is image | photographed and image data is acquired (step 40). Next, the process proceeds to a step of analyzing the acquired image data by the image analysis unit 32.

In the image analysis step, first, differential processing is performed on the photographed image, and the gradient of the luminance change is converted into an image expressed by brightness (step 41).
Next, the lead portion and the portion of the eyelet around the glass sealing portion are removed by masking, and a portion that is not required for image processing is removed (step 42).
Next, the brightness of the processed image is detected, and the slope of the luminance change is measured (step 43). The brightness of the processed image corresponds to the gradient of the luminance change by the differentiation process in the previous step. Therefore, the brightness distribution at each point in the image is detected and the brightness distribution in the image is obtained to obtain a frequency distribution table for the gradient of the luminance change.

  The brightness of the image data of this embodiment is in the range from 0 to 255. The black part in the image has a brightness of 0, and the part where the image of the light source is clearly visible is close to 255. Specifically, the brightness frequency distribution is obtained by detecting the brightness of each point (each unit cell portion) in the image, thereby obtaining a frequency distribution table for the brightness from 0 to 255.

  The inclination (brightness) of the luminance change obtained by the image analysis reflects the focus state of the image of the light source obtained by photographing the glass sealing portion with the CCD camera 28. That is, when the image of the light source of the obtained image is in focus, the image becomes bright, and when the image is not in focus, the brightness decreases. Since the focus position of the imaging optical system is set with reference to the surface position of the eyelet, the fact that the image of the light source is in focus means that the surface position of the glass 14 of the glass sealing portion is not deviated from the surface of the eyelet. (Close to the reference position) means that the image of the light source is not in focus means that the position of the surface of the glass 14 is displaced from the position of the surface of the eyelet.

FIG. 5 shows a graph representing the image of the glass sealing portion obtained by the CCD camera 28 and the brightness of the image of the light source shown in the image (the horizontal axis of the graph is the direction intersecting the image).
FIG. 5A shows a position where the surface of the glass 14 of the glass sealing portion is close to the surface of the eyelet, that is, a state where the image of the light source is in focus. FIG. 5B shows a case where the image of the light source is not in focus. By comparing the two graphs, it can be seen that the brightness of the image of the light source is strong or weak.
As shown in FIGS. 5A and 5B, by comparing the brightness of the image of the light source of the image data acquired by the CCD camera 28, it is determined whether the image is in focus, that is, a glass seal. It can be known whether or not the surface position of the glass 14 at the stop portion is greatly displaced from the surface of the eyelet.

  In step 41 described above, the image data acquired by the CCD camera 28 is differentiated and converted into an image representing the slope of the luminance change of the light source (the rate of change of the luminance change). This is because when the acquired image data is compared only by brightness (luminance), the image may appear bright even if the gradient of the luminance change is small, and the focus characteristics of the image may not be accurately reflected. It is.

After performing differential processing on the image data and removing the lead portion that is not necessary for image processing and the eyelet portion around the glass sealing portion, the frequency of the change in luminance of the processed image is measured, and the luminance change is measured. A frequency distribution table for the inclination is acquired, and pass / fail is determined based on the result (step 44).
In the apparatus according to the present embodiment, the gradient of brightness change (image brightness) is distributed in the range of 0 to 255. Therefore, the threshold value for determining good or bad is set as appropriate.
6 to 9 show a state in which a glass sealing portion is photographed and image-processed with respect to an actual glass terminal.

FIG. 6 is an image obtained by subjecting image data to differential processing and removing unnecessary portions of leads and eyelets. In the sample of FIG. 6, the surface of the glass 14 of the glass sealing portion is concave.
In the frequency distribution table obtained by measuring the gradient (brightness) of the luminance change for the image after this processing, the frequency of the gradient of the luminance change is 3275 when the gradient value of the luminance change is 255 or more, and the gradient value of the luminance change is 234 to 254 The total frequency was about 300 degrees.
When the image data of the glass sealing part was processed and measured, the brightness in the image was 200 or less when the image of the light source was not in focus. Judgment criteria (threshold values) for determining good or bad from image data will be set as appropriate, but here the brightness that is considered to be the region where the image of the light source is in focus is in the range of 234 to 255 , I am investigating how the frequency will be.

In the measurement data of FIG. 6, since the frequency of data with brightness of 255 or more is overwhelmingly large, the image of the light source is in focus accurately, that is, the amount of dent on the glass surface from the surface of the eyelet is slight. (Good product).
Further, since the image of the light source of the ring illumination unit 24 is clearly separated into a double ring shape and appears continuously in the circumferential direction, it can be seen that the surface of the glass 14 is a uniform surface with a good balance as a whole. .

FIG. 7 is an example of a sample in which the surface of the glass 14 of the glass sealing portion is convex. Differential processing is performed on the image data, and the lead and eyelet portions that are unnecessary for the image processing are removed.
According to the frequency distribution table obtained by measuring the brightness level of this image, the brightness with a brightness of 255 or more is 247 and the brightness with a brightness of 234 to 254 is about 90 degrees. Compared to the glass sealing portion shown in FIG. 6, since the frequency of 234 or more is small, the displacement amount of the glass surface from the eyelet surface of this sample is considered to be larger than that of the sample of FIG. Judged as non-defective.
Moreover, in this sample, since the image of the light source of the ring illumination part 24 appears only about a half circumference, it turns out that the surface of the glass 14 is inclined.

FIG. 8 is an example of a sample in which the surface of the glass 14 is concave.
In the frequency distribution table obtained by measuring the brightness of the image shown in FIG. 8, the brightness with a brightness of 255 or more is 349, and the brightness with a brightness of 234 to 254 is about 200 degrees in total. . Since this sample also has a frequency of 234 to 255, it is determined as a non-defective product.
Moreover, in this sample, since the image of the light source of the ring illumination part 24 is not continuous in the circumferential direction, it can be seen that the surface of the glass 14 is inclined.

FIG. 9 is an example of a sample in which the surface of the glass 14 is concave, and the amount of dent of the glass 14 with respect to the eyelet surface is large.
In the frequency distribution table obtained by measuring the brightness of the image shown in FIG. 9, the frequency at which the brightness is 255 is 0, and the brightness from 234 to 254 is all 0. The measurement results of this sample are in contrast to the measurement results shown in FIGS. 6, 7, and 8, where no point where the brightness is 234 or more is found. Therefore, this sample is determined to be defective. Since the surface position of the glass 14 is greatly deviated from the surface position of the eyelet (becomes low), a bright spot cannot be obtained in the image.

FIG. 10 shows the results of measuring the frequency distribution of image data and brightness, together with the actual measurement values of the dent amount from the eyelet surface to the surface of the glass 14 for some samples determined as defective products.
The samples shown in FIG. 10 are six types of samples in which the dents from the eyelet surface of the glass 14 are 0.5323 mm, 0.5797 mm, 0.6634 mm, 0.7434 mm, 0.7842 mm, and 0.8793 mm. Comparing the image data for these samples, it can be seen that the image of the light source becomes blurred as the amount of dents in the glass increases. As the amount of dents in the glass increases, the focus of the light source image increases.

  In addition, the result of measuring the brightness frequency distribution for the image indicates that none of the samples has a brightness in the range of 234 to 255. This measurement result shows that it is effective to determine the quality of the product based on the brightness frequency distribution obtained by image analysis. The standard for determining pass / fail based on the frequency distribution of brightness may be set as appropriate. For example, if there is even one frequency within the range of 234 to 255, the product is determined to be non-defective. In the case where there is not even one, a method of making a defective product can be considered.

In the present embodiment, various conditions such as the depth of field of the optical system are set as conditions for allowing the dent amount from the eyelet surface of the glass sealing portion to 0.5 mm. Examining the frequency distribution in the brightness range of 234 to 255 is also convenient, and the determination condition may be set as appropriate depending on the product or the determination condition of pass / fail.
In the above description, the “brightness” when the brightness is in the range of 234 to 255, for example, does not indicate the brightness itself acquired as image data, but the image after performing the differentiation process. Brightness. Of course, if the brightness distribution in the image without the differentiation process is compared and the frequency distribution of the brightness is measured, and the quality can be judged based on the result, the image differentiation process is not performed. Also good.

  The method for inspecting a glass sealing part according to the present invention is to include an image of a light source of a ring illumination part in the glass sealing part, detect a focus state of the image of the light source, and detect the state of glass in the glass sealing part (filling State, planar shape of glass). Therefore, the measurement accuracy is inferior to the method of accurately measuring the surface position of the object to be inspected using the position sensor, but the glass surface displacement amount is 0.5 mm as in the above-described embodiment. In the case where the measurement error is allowed up to about ± 0.1 mm, it can be used effectively.

Further, in the above embodiment, the periphery of the lead 10 is sealed by using the ring illumination unit 24 as the illumination body and setting the glass sealing unit so that the ring-shaped light source provided in the ring illumination unit 24 is reflected. The surface state of the glass 14 to be stopped can be easily detected over the circumferential direction. For example, if the image of the light source reflected in the glass sealing part is not continuous in the circumferential direction, it can be known that the surface of the glass is inclined.
The illuminator can detect the surface condition in the circumferential direction of the glass even if the light source is arranged continuously at a predetermined interval in the circumferential direction instead of arranging the light sources continuously in the circumferential direction. it can.
In this embodiment, even if the position of the glass surface of the glass sealing portion is one, it will be a non-defective product if it exceeds the reference position (the glass dent amount is 0.5 mm or less). It is effective to use the light source.

  The above-described embodiment is an example in which the lead of the glass terminal is applied to the glass-sealed portion, but the present invention is not applied only to the inspection of the glass-sealed portion where the lead is sealed. For example, when the through-hole provided in the base is sealed with glass, the same can be applied to the case where the sealing state with the glass is inspected.

It is explanatory drawing which shows schematic structure of the test | inspection apparatus of a glass sealing part. It is the structure of a glass sealing part, and the image data of a glass sealing part. It is explanatory drawing which shows the light reflection by the glass of a glass sealing part. It is a flowchart of an image process. It is a graph which shows the brightness of the image of the image data and the light source in an image. It is an image obtained by differentiating image data and removing unnecessary portions. It is an image obtained by differentiating image data and removing unnecessary portions. It is an image obtained by differentiating image data and removing unnecessary portions. It is an image obtained by differentiating image data and removing unnecessary portions. It is a figure which shows image data and frequency distribution about the glass sealing part of inferior goods. It is sectional drawing which shows the glass sealing part of an optical semiconductor device.

Explanation of symbols

10 lead 12 eyelet 12a insertion hole 14 glass 20 glass terminal 21 lead 22 set base 24 ring illumination part 24a LED
24b Aperture 25 Illumination power supply 26 Optical lens 28 CCD camera 30 Imaging optical system 32 Image analysis unit 34 Input unit 36 Monitor

Claims (8)

A support part for supporting an object to be inspected with a glass sealing part at an inspection position;
A ring illumination unit disposed above the object to be inspected and illuminating the object to be inspected, wherein a light source is disposed in a ring shape;
An imaging optical system for photographing the glass sealing part together with an image of the light source of the ring illumination part reflected in the glass sealing part through the opening of the ring illumination part;
Analyzing the image data photographed by the imaging optical system, and comprising an image analysis unit for analyzing the surface state of the glass in the glass sealing unit ,
The image analysis unit, the image data and the differential processing, glass sealing of the means for converting the brightness of the image data, characterized that you have a means for measuring the brightness histogram of the image data Stop part inspection device.   The imaging optical system has a depth of field so that the displacement of the surface position of the glass in the glass sealing part is captured as a change in the focus state of the light source image of the ring illumination part reflected in the glass sealing part. The glass sealing part inspection device according to claim 1, wherein: The glass ring inspection apparatus according to claim 1 or 2 , wherein the ring illumination unit includes a light source in which a plurality of LEDs are arranged in an annular shape. It is an inspection method for inspecting the surface state of glass provided in the glass sealing portion of an object to be inspected having a glass sealing portion,
Illuminating an object to be inspected having a glass sealing part with a ring illumination part, and using the imaging optical system, photographing the glass sealing part together with an image of the light source of the ring illumination part reflected in the glass sealing part When,
Analyzing image data captured by the imaging optical system by an image analysis unit, and analyzing the surface state of the glass in the glass sealing unit,
The imaging optical system is set so that the displacement of the surface position of the glass in the glass sealing part is captured as a change in the focus state of the image of the light source of the ring illumination part reflected in the glass sealing part,
The step of analyzing the surface state of the glass includes a step of measuring the frequency distribution of the brightness of the image data, and detecting the state of the surface of the glass based on the frequency distribution of the brightness of the image data. A method for inspecting a glass sealing portion characterized by the above. In the step of illuminating the object to be inspected by the ring illumination unit,
The method for inspecting a glass sealing part according to claim 4, wherein a ring illumination part in which light sources are arranged in an annular shape is used. In the step of analyzing the surface state of the glass by the image analysis unit, the step of differential processing the image data,
6. The method for inspecting a glass sealing portion according to claim 4 , wherein in the step of measuring the brightness frequency distribution of the image data, the frequency distribution is measured for the image data subjected to the differentiation process. In the step of analyzing the glass surface state by the image analysis unit,
The method for inspecting a glass sealing portion according to claim 6, further comprising a step of removing unnecessary portions of the image data. It is a case where a glass terminal provided with a glass sealing part in which a lead is glass-sealed in an eyelet is an inspection object,
In the step of illuminating the object to be inspected by the ring illumination unit, a ring illumination unit in which a light source is arranged in an annular shape is used,
In the step of analyzing the surface state of the glass by the image analysis unit, the step of differentiating the image data, the step of removing unnecessary portions of the lead and the eyelet from the image data, and the differentiation process were performed. The method for inspecting a glass sealing portion according to claim 4, further comprising a step of measuring a frequency distribution for the image data.